The present invention relates generally to apparatus and processes for drying grain, and more particularly to an apparatus and process for preheating corn to be dried in a corn dryer by utilizing waste (or exhaust) heat from the corn dryer.
Cereal grains, particularly corn, are often harvested with a moisture level in the grain that is too high to permit storage of the grain without damage. Corn is often harvested at 18 to 38 percent moisture and must be dried to 14 to 15.5 percent moisture for safe storage. In order to achieve this drying quickly enough to prevent spoilage of the grain, artificial drying processes are often employed that utilize heated air which is forced through the grain in either batch or continuous flow arrangements.
The quality of the grain is more greatly affected by the process of drying than by any other grain handling operation. The main dryer operating factors affecting grain quality are air temperature, airflow rate and residence time. The three conditions together determine the drying rate and maximum temperature of the grain being dried, and establishes the final quality of the dried lot. It is known that excessively rapid drying of moist grain causes stress cracking of the kernel, which can make the grain more susceptible to breakage during subsequent handling operations.
One method of reducing thermal shock to the corn kernel caused by rapid heating of the grain in the corn dryer is to pretreat the corn before it enters the corn dryer by preheating the corn. The temperature gradient created in the corn kernel in the corn dryer during rapid heating is thereby reduced, which in turn reduces stress cracking
Thus, it would be desirable to provide a process, and its related apparatus, that provides for a more uniform preheating of corn prior to entry into the corn dryer per se, which is not detrimental to the quality of the corn. It would also be desirable to provide such a process and apparatus which is efficient in the use of energy during its operation.